Sacramento daily record-union. [volume] (Sacramento [Calif.]) 1875-1891, 1887-09-03
SCALE INSECTS.
THE USE OF HYDROCYANIC ACID
TO EXTERMINATE THEM.
A Further Report ofthe Experiments
Made in this Line at the
State University.

tNoTE.-As stated in previous University
bulletin no. II, June II, 1851 special investi
CATION was undertaken by this station at the re-
quest of range-growers of San Gabriel, Los
Angeles county, to determine the practicabilily
and efficiency of gaseous insecticides The re
suits obtained were so satisfactory that the
orange-growers who bore the extra expenses OF
the first experiments urged the advantages OF
continuing the work, and the Board OF super
yisors made an appropriation TO cover expenses,
the work TO be done under the auspices OF the
County Horticultural Commissioners For this
reason the following description of later expert
ments, and their results takes the form of a
report to the local authorities of Los Angeles
county,:
To the Board Of horticultural Commission
ers'of Los Angeles Colaty-GENTLEME |
herewith transmit 4 preliminary report of
Investigations, carried on at your request,
relating to the use of gas rs an insecticide
against the cottony cushion scale insect
(Iceryd PURCHASE. The work was a contin-
uation of that carried on some time ago,
and consists mainly in devising means for
the easier application of the gas, which was
found by the earlier experiment to be the
most efficient.
In resuming the work, to carry out the
general principles of application as set
forth i'll the last report, it was found neces-
sary to vary considerably the form of appa-
ratus and preliminary preparation of ma
terials, for the purpose of increasing the
rapidity and certainty of application. A
fan-blower, capable Of carrying heavy
volume OF wind, replaced the pump pre-
viously used, and this necessitated change
in the form of the generator.
Many experiments were made TO de-
termine the most convenient methods for
using the chemicals. The old way of mix
ing the soda and cyanide in the generator
was found to be too slow and uncertain to
be practicable. Often heavy crystalline
coating formed around the mixture and
prevented complete action when the acid
was added; again, when the two salts were
not mixed, the usefulness of the carbonate
as a protection to the foliage was often
leSsened. In order TO avoid this difficulty.
II became necessary to reverse the order of
application and inject slowly the salt mix
ture upon the acid, as given in the direc-
tions below.
An attempt was made TO use each ingre-
dent separately the soda being in a solid
form, but the same difficulties of uncer-
tainty and slowness were experienced.
The generator, in general terms. consists
of a sheet-iron cylinder, or tank, held be-
tween two pieces of plank. one of which
forms the cover, and the other movable
base which Is carried up and down by an
eccentric placed beneath. The cover holds
two receivers lone for the acid and one for
the cyanide and Soda and two tubes OPEN
ing INTO the exit pipe which passes over
the generator from the blower. A heavy
volume of air, carrying with it the gas. is
forced by the blower into the tent through
81 inch pipe, and after diffusing is again
carried back by a similar pipe to the
blower, thus establishing Il continuous cir
culation and stirring up the gas during the
treatment
In the pipes leading to and from the
tent and two joints-one at the elbow close
to the generator, used as disconnecting
joint when the apparatus is moved; the
other, about three feet from this point. is
used as the disconnecting joint when two
tents are worked with the same generator.
and becomes only flexible joint when one
tent is used; the former in this case be-
comes the disconnecting joint The open
ing of the injecting pipe is covered with
perforated cap, which distributes the pas
when pumped into the tent
The tent for covering the tree is made
of heavy bed-ticking, thoroughly oiled
with linseed oil. This cloth serves the
purpose best, as it Is very closely woven. is
pliable and easily folded. Practice has
shown that much labor and time can be
saved, and less injury done to the tree by
having tent which passes easily over the
tree, with cloth enough to make close
connection at the bottom with the earth.
The cloth is folded out at the bottom
rather than folded in, as in the older treat
ment, and its margin covered with dirt,
thus increasing the area of soil treated
without materially increasing the volume
within which is to be filled with gas.
The tent should be made somewhat bell
shaped, having "dange' at the bottom of
sufficient size to move outside of the main
tent at all times, and should fold over like
a glove when the tent is removed. 1t
should also be large, so that the points of
attachment Of the side guy ropes may be
drawn close to the pulleys in the corner Of
the frame; thus, when wide-spreading
trees are to be treated, the tent can easily
be drawn over any branches included with
in the frame.
"The support of the tent, devised by
Mr. Titus, is a very ingcniously contrived
seafiolding mounted on wheels, which serve
to move it from one tree to another. It's
dimensions are rs feet high. with base
20x20 feet. Its upper part is 20x12, and
carries upon the top roller made of gal
vanized iron, inches in diameter and II
feet long, upon which the tent is rolled
when taken from the tree Side guy-ropes
are attached to the bottom of the tent and
run through pulleys at the upper corners
of the scaffold. They are used to open the
tent when it is to be dropped over the
tree, and TO fold it up when it is removed.
The lightness of the apparatus allows it of
being easily moved by two men, who oper-
ate the whole. If necessary, two or more
tents can be handled by the same scaffold-
ing, one tent being left over the tree while
the scaffolding is removed to the next"
Later experience shows that it is advan-
tageous to have frame for each tent, with
one generator to supply the gas for two
tents. Such an arrangement can be ham
died by one crew of men without loss of
time.
Acid.-Much Of the success of the oper-
alton depends upon the use of acid of the
proper strength, and it should be specially
urged that the acid be of the strength
recommended in the table of doses given
below, This any workman can determine
by the use OF Baume bydrometer, which
can easily be procured with sufficient in
structions for its use. If the acid is not of
the proper strength, the table below will
show the amounts to be used corresponding
to the degrees indicated by the hydrometer.
Thus, if the acid only shows 500, use the
column marked 500 Baume in place Of that
of the 650 in the regular prescribed doses
of acid.